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April 15, 2010

Food of the Gods

Mushrooms are one of my favorite foods. During a trip to Japan a couple of years ago I was delighted to discover that pretty much the whole nation shares my taste for edible fungi. Mushrooms for breakfast! Japan is a major mushroom producer and importer, so it's not surprising that Japanese biologists spend a lot of time studying mushrooms. Presumably most of them are not as borderline-lunatic as this guy mentioned in an earlier 'blog post.

Because they're such a favorite, mushrooms show up in Japanese pop culture -- most famously in the Mario games from Nintendo, and in the cult movie classic Matango: Fungus of Terror.

And now Japanese scientists have discovered that lightning may help mushrooms grow. (Or, more accurately, may encourage mushrooms to put forth the fruiting bodies that we eat -- the real mushroom is the network of mycelia laced through the organic material the mushroom feeds on.) Applying high-voltage electrical pulses to logs seeded with mushroom spores nearly doubled production of edible mushrooms. So this is serious business and is likely to attract the attention of commercial mushroom growers all over the world.

The question of why this works is a bit more mysterious. The researchers were supposedly inspired by Japanese folklore about mushrooms spawned by lightning, but in point of fact they used pulses considerably weaker than actual lightning strikes. A direct jolt of lightning would literally vaporize the mushrooms, which seldom improves either the taste or the crop yield.

The most likely reason is simply stress. The electrical pulses put the mushrooms under stress, just like drought, heat, predation, or whatever. It's common for organisms under stress to respond with a burst of frantic reproduction. "I'm dying but my spores will live on!"

But since I'm not really a scientist, I can speculate more widely. It's just barely possible that the mushroom response to lightning is a specific adaptation. Follow my reasoning here: mushrooms grow in oak logs. In the wild, oaks grow tall and are often struck by lightning (the oak was sacred to lightning gods like Zeus and Thor because ancient Europeans noticed which trees those boys seemed to enjoy zapping the most). Lightning generally happens in conjunction with rainstorms, especially in the temperate forest environments where you find oaks and mushrooms. So if you're a mushroom, lightning means wet dead oak trees -- the perfect environment for new spores to find a home.

It's even testable: compare the response of forest mushrooms to lightning with the effects of electricity on varieties from other environments. If, say, grassland species of mushroom don't increase their fruiting as lavishly as forest types, then I am not a crackpot. About this, anyway.